The invention relates to a hermetically encapsulated oil-lubricated rotary piston compressor with a horizontally disposed, at least partly hollow crankshaft, where the lubricating oil is sucked up from the oil sump by a dynamic vacuum created in the compressed gas line and is conveyed together with the compressed gas into the hollow part of the crankshaft, which has radial bores inside the cylinder housing for supplying oil to the relatively moving surfaces of the compressor.
Hermetically encapsuled, oil-lubricated rotary piston compressors with horizontally disposed crankshafts are employed, because of their compact construction, in such appliances as household refrigerators and air conditioners where the space needed should be minimized. Because the crankshaft does not dip into the oil sump at the bottom of the housing, additional measures are necessary for supplying oil to the rotating parts of a compressor of this type. Such measures have included an oil pump driven for example by the crankshaft, and also arrangements where a vacuum created in the flowing compressed gas sucks the lubricating oil into the interior of the crankshaft.
A hermetically encapsulated, oil-lubricated rotary piston compressor with horizontally disposed hollow crankshaft is known from U.S. Pat. No. 4,391,573. Here, the lubricating oil is conveyed by the compressed gas ejected from the compressor into the hollow crankshaft. Inside the cylinder housing, the crankshaft has radial bores through which the lubricating oil reaches the relatively moving surfaces of the compressor for lubrication and sealing. The compressed gas (ejected by the eccentric rotary motion of the rotary piston out of the pressure chamber of the compressor via the outlet opening) is conducted, via a line system situated outside the cylinder housing and firmly connected with it, to the end of the hollow crankshaft away from the drive side. A part of this line system consists of a horizontal outlet pipe which is placed in the oil sump and is provided with an opening into which a vertical suction pipe leads. The upper end of this suction pipe protrudes into the outlet pipe and has a beveled opening and forms in this manner a constriction in the outlet pipe. This produces a dynamic vacuum and the lubricating oil is sucked into the outlet pipe and transported further into the hollow crankshaft. Because the suction pipe ends near the bottom of the compressor housing wall of the hermetically encapsulated rotary piston compressor, the oil supply can still be maintained even at slight inclinations of the compressor. During rotation of the compressor about the axis of the crankshaft or about an axis parallel thereto, however, the oil supply is interrupted if the opening of the suction pipe is no longer in the oil sump.
One object of the invention is to provide a hermetically encapsulated, oil-lubricated rotary piston compressor where the oil supply is not interrupted by any rotation of the compressor about the horizontal axis of its crankshaft or an axis parallel thereto.